Physics 2012 JAMB Past Questions - Question 48: The p-n junction diodes can act as rectifiers because they

Correct Answer

A

Explanation

P-N junction conducts current when forward biased and blocks current when reverse biased.The p-n junction diodes can act as rectifiers because they exhibit a property called rectification. Rectification is the process of converting alternating current (AC) into direct current (DC).

In a p-n junction diode, the p-side is doped with a material that has an excess of positive charge carriers (holes), while the n-side is doped with a material that has an excess of negative charge carriers (electrons). When a forward bias voltage is applied across the diode, the positive terminal of the voltage source is connected to the p-side, and the negative terminal is connected to the n-side.

During forward bias, the excess holes from the p-side and excess electrons from the n-side move towards the junction, creating a region near the junction called the depletion region. This region becomes very thin, allowing current to flow easily in one direction. This is why a p-n junction diode acts as a rectifier, allowing current to pass through in the forward direction (from p to n) while blocking current in the reverse direction.

By controlling the bias voltage, p-n junction diodes can be used to convert AC to DC by allowing current to flow only during the positive half-cycle of the AC waveform. This rectification property makes p-n junction diodes essential components in various electronic circuits, such as power supplies and signal processing circuits.